The time is the distant future. Earth has been rendered uninhabitable for much of the year by terrible storms during which its only city, Center, constructed around a natural cave system, is sealed from the outside.

Mischa, a young thief whose capabilities are enhanced by hereditary mutation, is trying to escape with her drug-addicted brother from the dominance of her uncle. So when a starship arrives commanded by the twin alien pseudosibs Subone and Subtwo, Mischa seizes her chance. She is soon assigned for training to Jan Hiraku, who quickly realises that Mischa has immense abilities. All goes well until Subone, in a moment of cruelty, lures Mischa's brother into a fight and then kills him. Mischa attacks Subone and both she and Jan have to flee the wrath of the brothers and take refuge in the deep caves underneath the city.